The main raw materials of CCL include composite foil, reinforcing fiber cloth, epoxy resin, curing agents, accelerators, solvents, fillers, etc., which is closely related to the process performance, processing performance, the overall performance of the final product during the production process of CCL. The laminate with one or both two sides of the substrate coated with a metal foil is called CCL, mainly for the production of printed circuit boards, is widely used in the products of telecommunications, mobile communications, computers, instrumentation, digital TV, digital audio, satellite, radar and others. In recent years the CCL has been used in solar cells, LED lighting, LED backlight, flat panel displays, automotive electronics and other new products field. In the electronic complete-machine products, CCL plays the role of the three elements which are load components, the circuit interconnection, and insulation between the circuits.
The wide use of this epoxy resin formula in CCL is due to its excellent machining performance before curing and excellent adhesion, mechanical strength, thermal dispersion, electricity performance and chemical resistance after curing. Besides, high density and three-dimensional network structure of the cured epoxy resin make it extremely durable hard materials, which can bear the influence of a wide range of environmental conditions. In meantime, after curing, the crosslinked network structure of epoxy resin makes it difficult to remove, recycle and reuse. Essentially, the cross-linking reaction applying polyamine and epoxy resin is irreversible, thus, this material can't be remelt, remolded without loss, or easily dissolved.
The CCL prepared by thermosetting epoxy resin with a combination of copper foil and fiber can be applied to the field of printed circuit board (PCB). The manufacturing process of PCB generally goes through the film plate making, pattern transfer, chemical etching, via hole and copper foil process, flux and solder resist process and other processes. Epoxy resin after curing is difficult to decompose and melt. Accordingly, epoxy based circuit board is difficult to recycle.
At home and abroad, the recycling technology of waste printed circuit board is mainly three categories: the first one is wet processing technology, including pickling, corrosion and others; the second one is fire treatment technology, including incineration, pyrolysis, direct smelting and others; the last one is physical and mechanical processing technology, including crushing and sorting processes. In general, these methods have their limitations in varying degrees, the processing scale of fire treatment technology is largest, the recovery of wet processing technology for metal is higher, but wet processing technology and fire treatment technology generate enormous environmental pollution and the environmental cost is very large. And the physical and mechanical treatment method, with a small investment and recovering metal, can not achieve the recovery of fiber and resin. Therefore, the effective and feasible environmental recycling method of waste material is still a question to be addressed in the material field.